Mammals
Gibbon
Hylobatidae · also called gibbons, lesser apes
A gibbon is an ape that traded size and strength for pure agility. Small, long-armed, and tailless, it lives almost its entire life in the canopy of Southeast Asian rainforest, swinging hand over hand at highway speed, and every morning a mated pair announces its territory with a loud, coordinated song. Nearly every gibbon species is now sliding toward extinction.
Overview
Gibbons are the family Hylobatidae, about 20 species of small (5–12 kg) apes — the lesser apes, to distinguish them from the great apes, though they are no less ape for it. They live in the tall closed-canopy rainforest of Southeast Asia and eat mostly ripe fruit, especially figs, tracked around a family territory.
The fastest brachiator
A gibbon moves by brachiation — swinging beneath the branches with its very long arms and hook-shaped hands — at up to 55 km/h, clearing gaps of 15 m in a single leap. No tree-living mammal is faster or more acrobatic in the canopy.
Pairs and songs
Unusually among apes, gibbons live in monogamous family groups, and each dawn a pair sings a coordinated duet that carries over a kilometre, advertising the territory and reinforcing the bond. Each species has its own song. The siamang amplifies its calls with an inflatable throat pouch, producing some of the loudest sounds of any land animal.
Status
Endangered as a family — almost every species is Endangered or Critically Endangered, hit by the clearing of rainforest for oil palm and rubber, hunting, and the pet trade. The Hainan gibbon, at about 40 individuals, is the rarest ape on Earth.
Gibbon: common questions
Is a gibbon a monkey or an ape?
A gibbon is an ape. It has no tail, has the broad chest and highly mobile shoulder joint of an ape, and belongs to the ape branch of the primate tree along with orangutans, gorillas, chimpanzees, bonobos, and humans. Gibbons are called the lesser apes only because they are much smaller than the great apes, not because they are any less ape. They are, however, the earliest branch to split off from the rest of the apes, more than 15 million years ago, so they are the most distant ape relatives of humans.
How can gibbons swing so fast and so far?
Their whole body is built for brachiation, swinging hand over hand under branches. A gibbon's arms are far longer than its legs, its hands are long and narrow with a deep hook shape and a thumb set well back out of the way, and its shoulder joint rotates almost freely, letting the animal release one handhold and reach the next in a continuous pendulum swing. Moving this way, a gibbon can travel at around 55 kilometres per hour through the canopy and cross gaps of up to 15 metres in a leap, faster and more surely than any monkey.
Why do gibbons sing?
Gibbon song is mainly about territory and pair bonds. A mated pair sings a coordinated duet, usually soon after dawn, with the male and female taking turns and building to a climax, and the sound carries over a kilometre, telling neighbouring groups that this stretch of forest is taken. Singing together also appears to strengthen and signal the pair bond, and unmated animals sing solos that function as advertisements for a mate. Each species has a distinctive song, and researchers can identify gibbons, and even individual groups, by ear.
Why are gibbons so endangered?
Gibbons depend on large areas of tall, unbroken rainforest with a continuous canopy they can swing through, and that habitat is disappearing fast in Southeast Asia, cleared for oil palm and rubber plantations, logged, and cut up by roads and farmland into fragments too small to hold a viable population. On top of habitat loss, gibbons are hunted for meat and for use in traditional medicine, and infants are taken for the pet trade, which usually means killing the mother. The result is that nearly every gibbon species is now Endangered or Critically Endangered, and the Hainan gibbon has been reduced to about 40 animals.